Reducing and removing snow loads on farm buildings
With heavy, wet snow in the forecast, many farmers in the path of the latest storm are keeping a close eye on their buildings, especially with the threat of increasing snow loads, which can cause the roof on a farm building to collapse.
Snow loads are the downward force on a building’s roof accumulated by snow and ice.
Brian Holmes, a retired University of Wisconsin-Extension agricultural engineer told Wisconsin Public Radio that farm buildings are more likely to be damaged by snow on roofs because they are exempt from state building codes. Additionally, farm buildings tend to be older. The moist environment caused by livestock also compromises the strength of the structures.
Here’s how to protect yourself, your building, your equipment and your livestock from the damage a snow load can cause.
When it comes to removing snow, using a systematic method will reduce the risk of injury or death to those working on the roof and barn occupants. Cornell University provided some do's and don'ts of removing snow from barns after assessing the building's structural situation before getting on the roof to clear snow.
A wood structure that is creaking or moaning or if there is bowing of rafters, headers, or truss bottom chords may be signs of can be signs of a wood structure that is going to fail. Pre-engineered metal structures are more likely to fail without warning, according to Cornell University.
What to do
Using a systematic, zone removal approach is the best way to remove roof snow from a barn. The number of zones depends on the width of the barn or the span of the trusses, starting with the area by the eaves and working up to the peak.
Snow should be removed from both sides equally, taking care not to pile the snow up against the barn walls, which could result in ventilation challenges or building failure.
What not to do
Don't remove snow unequally from a barn roof or pile large piles of moved snow on the roof.
Unbalanced loads, from one side of the roof to the other, can cause the unloaded side of the truss to lift. It's better to work back and forth from side to side or have a crew working simultaneously on each side.
While clearing snow, don't create piles of moved snow on one spot of the roof. The roof might be able to support a load of snow if it is spread out equally across the roof, but piles of snow on the roof may cause failure in those areas. Cornell University recommends removing snow gradually working from the lower areas of the roof to the peak.